1. Field of the Invention
The invention relates to electronic signal communication, particularly to signaling protocol and related circuitry for enabling data communication through bus lines.
2. Description of Background Art
The use of an assembly of electrical conductors known as a "bus" is common in electrical circuit design. For example, buses are used often in microprocessor-based designs for connecting signal lines between the microprocessor and other system components, such as memory devices, input/output interface and other controller circuitry, each component being coupled typically to a common bus.
Using a shared approach, bus signal lines are thus used, when available, by various components in the system. To avoid bus contention, which arises when components access simultaneously the same signal lines, bus arbitration means are provided typically for granting, according to some specified access criteria, signal lines to certain components requesting access to the bus.
In addition to granting priority to access signal lines, conventional bus arbiters serve to synchronize data signal transfer as well as arbitration signal "hand-shaking" events which occur between the bus arbiter and source and destination components coupled to the bus. In particular, conventional bus arbiters provide a single arbitration clock signal from which system components may synchronize for both arbitration and data transfer purposes.
However, because the rate at which the source or destination components typically transmit or receive data signal to or from the bus does not necessarily match (and, in fact, may often be quite faster than) the arbitration clock rate, overall bus bandwidth using conventional bus synchronization schemes is thereby limited significantly.
Moreover, because bus control is maintained continuously during the entire arbitration process, i.e., by a bus master, not only between bus request and grant events, but also until data transfer is confirmed, valuable bus bandwidth is wasted further during conventional bus arbitration.
Therefore, there is a need to provide a more efficient bus communication protocol whereby overall bandwidth is significantly improved.